WGA54G - Support more than one MAC Address?

I bought a WGA54G - Gaming adapter. I don't want it for gaming, I want it to be a wireless bridge.

I have a network, BEFW11S4 at the core. Have some equipment in my garage that I want to connect, so got the gaming adapter. Set it all for my WEP and SSID and it works like a charm - with one device.

The equipment is a rack of routers for certification testing. Only need to conenct to the terminal server, so it works great for that. I decided to add a PC to the rack (and move some others out there), and it would seem that whatever device I ping FIRST works - the others get nowhere.

Is this a known limitation? IS this why it's a "gaming adapter" and not a wireless bridge?

Any help is apprecited. Again it works great - but only for the first device it sees.